Case report: two cases of mature oocytes found in prepubertal girls during ovarian tissue cryopreservation

To report two cases of mature oocytes found in prepubertal girls undergoing ovarian tissue cryopreservation (OTC). Case report. Large tertiary care children’s hospital and a private fertility clinic. An 8-year-old prepubertal girl with β-thalassemia and a 2-year-old girl with sickle cell disease who both underwent OTC before bone marrow transplantations. Laparoscopic right oophorectomy was performed in each patient. The ovarian cortical tissue was processed for slow freezing and long-term storage, and all oocytes were subsequently vitrified. Oocytes found at the time of OTC processing for fertility preservation. After a complete right oophorectomy, one mature metaphase II oocyte was discovered on tissue processing for OTC in each patient. Neither patient has yet returned for use of tissue or oocytes. To our knowledge, this is the first report of mature oocytes found during prepubertal OTC processing. These findings may indicate the need for increased research regarding prepubertal oocyte development and suggest that the technique of examining the media for both mature and immature oocytes at the time of OTC should become more widespread and perhaps recommended in prepubertal patients to optimize fertility preservation methods.